I am running GNU Guile 3.0.4 on MacOS Catalina.

When trying http-get to retrieve json from the Swedish smhi opendata i get this error:
In web/client.scm:
   525:24  5 (http-request _ #:body _ #:verify-certificate? _ #:port _ #:method _ # ?)
In web/response.scm:
   200:48  4 (read-response #<input-output: string 10b2198c0>)
In web/http.scm:
   225:33  3 (read-headers #<input-output: string 10b2198c0>)
   195:11  2 (read-header _)
    252:2  1 (parse-non-negative-integer _ _ _)
In ice-9/boot-9.scm:
  1669:16  0 (raise-exception _ #:continuable? _)

Reproduce like this:
scheme@(guile-user) [2]> (use-modules (web client))
scheme@(guile-user) [4]> (http-get "https://opendata-download-metobs.smhi.se/api/version/1.0/parameter.json" #:verify-certificate? #f)

Regards
Nic